Sen. Sanders’ letter alleges Clinton’s campaign has paid staffers from the Hillary Victory Fund, a joint fundraising venture between the DNC and the Democratic frontrunner.

The letter states the Hillary Victory Fund “reported receiving several individual contributions in amounts as high as $353,000 or more, which is over 130 times the $2,700 limit.“

Responding to what Clinton campaign manager Robby Mook described a “false attack,” Clinton’s camp released a statement which read:

“The Sanders campaign’s false attacks have gotten out of hand. It is shameful that Senator Sanders has resorted to irresponsible and misleading attacks just to raise money for himself.”

Mook followed with a demand Sanders drop his campaign’s lawsuit against the DNC for access to voter data files, and claimed the litigation is a “drain” on DNC resources and represents the frivolity of the Vermont senator’s campaign.

Clinton’s campaign later told the Washington Post that her “use of the fund is proper and that the state parties will benefit from the millions of dollars the joint fundraising committee is generating for the DNC.”

“There is absolutely nothing different in the way we have spent money and raised money with Secretary Hillary Clinton.”

The public back-and-forth between the two Democratic rivals comes amid two blockbuster fundraising events hosted by Democratic donors in California. Hollywood film star, George Clooney, hosted one such event.

Clooney asserted the money raised was not intended to entirely benefit Clinton, but to raise money for Democratic congressional campaigns.

“This fundraising arrangement that George Clooney and others have donated into believing that they’re giving money to the down-ballot candidates, two-thirds of that money is going actually to Hillary Clinton. In addition to that, $15 million of that money has gone into other operations that primarily benefit only Secretary Clinton.”

Weaver wasted no time connecting Clinton’s questionable fundraising in California to the Hillary Victory Fund and the DNC.

“There’s a little bit of question about how this joint-fundraising agreement is working. The Clinton people are doing something very, very unusual in the way that they’re operating this fund,” said Weaver.